Tallow is an important raw material for producing biofuels, such as biodiesel, and can be obtained by rendering animal fats, oil and grease. Meat processing wastewater contains animal fats, oil and grease as waste products that must be removed to clarify the wastewater.
Conventional treatment for clarifying wastewater includes using a clarifier or flotation unit, such as a dissolved air flotation or entrapped air flotation unit, to separate suspended solid particles, including fats, oil and grease, into a solid phase that floats up or sinks down in the treatment units. Unfortunately, conventional treatment removes less than 40% of the fats, oil and grease in the wastewater. Fats, oil and grease can form emulsions with the wastewater and are difficult to separate.
Demulsifying coagulants and flocculants can be used to aid in the removal of fats, oil and grease by breaking oil-in-water emulsions and agglomerating the oil particles. However, coagulants traditionally used often contain inorganic materials, which can be harmful to the environment and can leave residual metals in the fats, oil and grease. These metals become a source of contaminants in the tallow and biodiesel production, which is detrimental to biodiesel reactors and diesel engines.
What is needed is an improved and environmentally friendly process for removing fats, oil and grease from meat processing wastewater and recovering tallow.